Cement trough leaking

Our new plot has a concrete water trough built about ½ inch away from the ruin we plan to renovate.

The trough is 4,000 litres and would come in handy during dry months in Portugal.

In an attempt to fill it with recent rains we set up a tarpaulin to catch and direct rain but it seems the trough is leaking.  (No roof on ruin yet)

No visible cracks.

Not sure what's best going forward…

Repair the trough or pull it down?

Alternative seems to be 1000 litre plastic IBC which is popular amongst homesteaders in Portugal.

If we repair how best do we do this?

We are looking at painting with polymer waterproof liquid membrane.

Does it come down what is the least toxic option?

Thoughts, questions and suggestions appreciated.

A 4000L trough sounds amazing!

A quick search resulted in this website listing a few options.
If it gets direct sunlight, I would avoid plastic sealers.
Water glass might also be an option, but is rather costly.

I bumbled around the internet not sure what to look for.  That link you shared is very helpful. Thank you. Looks like products are available in Portugal as well.

It seems a shame to demolish existing structure.  What I don't want is to renovate the ruin and have 4000 litres flood the place in the future.

Sebastian Köln wrote:A 4000L trough sounds amazing!
this website[/url] listing a few options.
If it gets direct sunlight, I would avoid plastic sealers.
Water glass might also be an option, but is rather costly.

If it were me, I would clean it thoroughly ( e.g. pressure washer), fill any cracks if you find any, and coat it in a cement based waterproofing (e.g. thororseal).